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Greenhouse Effect/Transcript
Transcript Text reads: The Mysteries of Life with Tim and Moby Tim and Moby are walking outdoors on a winter day. Tim is wearing a heavy winter coat and a scarf. TIM: It's freezing. They walk into a greenhouse. TIM: Oh, much better. Tim reads from a typed letter. TIM: Dear Tim and Moby, What is the greenhouse effect? From, Iciar. The greenhouse effect is a warming-up of the earth from certain gases in our atmosphere. Gases like carbon dioxide, nitrous oxide, and methane are known as greenhouse gases when they occur in the atmosphere. Images represent individual molecules of the three gasses. MOBY: Beep. TIM: Well, it's similar to how we're keeping warm right now. Solar radiation, or rays of sunlight, comes in through the glass and heats up the air inside this greenhouse. That hot air is trapped inside, which makes a nice, warm, and humid environment for the plants. An animation shows sunlight shining through the glass roof and walls of a greenhouse. The interior of the greenhouse contains plants. It glows to signify that it's warm inside. MOBY: Beep. TIM: Right. Greenhouse gases are sort of like the panes of glass that make up a greenhouse but with some important differences. The main difference is this:once sunlight gets trapped inside a real greenhouse, its heat is stuck in there and can't really get back out into the surrounding air. An animation shows a greenhouse trapping heat from the sun. TIM: When sunlight travels into the earth's atmosphere, land, water, and plants on the earth's surface soak up most of that radiation. But then lots of that energy is sent back out into the atmosphere in the form of infrared radiation, or heat. Instead of just blocking the heat from escaping into space like the greenhouse glass does, the earth's greenhouse gases absorb heat and send it back down to the surface. That makes a kind of a heat loop. An animation shows Earth from space. Arrows indicate heat energy coming from the Sun, bouncing off Earth's surface, rising back into the atmosphere as heat, and returning to Earth's surface again. MOBY: Beep. TIM: Well, the end result is the same. The earth warms up, just like the inside of a greenhouse. An animation of Earth in space shows the planet glowing as it becomes warmer. TIM: Without these gases, our planet would be about 33 degrees Celsius colder, too cold for us to live here. An animation shows greenhouse gas molecules disappearing, along with a thermometer's mercury dropping. MOBY: Beep. TIM: Well, the earth has naturally heated and cooled over time. But if the greenhouse effect gets too strong, the earth could drastically warm up, which would cause climate changes and other environmental problems. Scientists believe this is already starting to happen, and they call it global warming. In the last one hundred years, the earth's average surface temperature has risen about three-quarters of a degree Celsius. An animation shows Earth from space, with a mercury thermometer demonstrating the temperature rise that Tim describes. TIM: That doesn't sound like a whole lot, but it's more than enough to cause glaciers and the polar ice caps to start melting. An animation shows melting icebergs floating in the ocean. TIM: If it keeps up, sea levels could rise high enough to flood coastlines, endangering the habitats of many plants, animals, and people. An animation shows a town being flooded. A person sits on a house's roof with a duck, and a trashcan floats by with a cat on it. TIM: Plus, the warmer temperatures themselves can be dangerous to life, both in the oceans and on land. An animation shows two small fish swimming next to a dying coral reef. An image shows a dead animal lying on the dry ground. TIM: Global warming may also change weather patterns all over the world. Like, it might increase the number and severity of floods, droughts, and storms like hurricanes. An animated world map shows two hurricanes forming in different parts of the world. TIM: Scientists are already predicting that temperatures could increase by up to six degrees Celsius over the next 100 years. MOBY: Beep. Moby looks worried. TIM: Well, scientists say the main cause of global warming is skyrocketing levels of greenhouse gases, especially carbon dioxide and methane. And they agree that most of it is likely due to human activity. MOBY: Beep. TIM: For one thing, the burning of fossil fuels puts more and more carbon dioxide into the air. Animations show a car's exhaust pipe and a factory's smokestack. Both are spewing pollution. TIM: Also, deforestation has reduced the worldwide number of plants and trees, which take in carbon dioxide and produce oxygen. Animations show a chopped-down forest and a large forest fire. TIM: And then there's our dependence on animals for meat and other products. The digestive systems of cows and other livestock produce methane, which is more than 20 times as powerful a greenhouse gas as carbon dioxide. An animation shows cattle grazing in a pasture. A cow burps loudly, and a cloud of gas drifts from its mouth into the air. TIM: It all adds up to one unavoidable conclusion. We need to work at reducing the amount of greenhouse gases that humans put into the mix. That's our best chance of keeping the earth on track. MOBY: Beep. Moby taps the wall of the greenhouse he and Tim are standing in. TIM: Oh, do we have to? Moby nods. They leave the greenhouse. As they walk, Tim quickly becomes cold again. TIM: Ergh. Category:BrainPOP Transcripts Category:BrainPOP Science Transcripts